Abstract: A steering apparatus includes a steering shaft; a steered shaft; a ball screw mechanism; and a motor. A plurality of rolling elements includes large-diameter rolling elements and small-diameter rolling elements. A prescribed diameter difference is set such that when a magnitude of power transmitted between a first screw groove and a second screw groove is a prescribed value or less, only the large-diameter rolling elements transmit the power between the first screw groove and the second screw groove, and when the magnitude of the power transmitted between the first screw groove and the second screw groove exceeds the prescribed value, both the large-diameter rolling elements and the small-diameter rolling elements transmit the power.

Abstract: A torque limiter is configured from a ring body and a spring-form part provided in the ring body. The ring body includes a band-form metal plate and is bent approximately into a C-shape along the circumferential direction of a motor shaft and a lock holder. The spring-form part is formed so as to be capable of radial elastic deformation. The spring-form part is configured from main protrusions arranged in a compressed state between the motor shaft and the lock holder, and from sub-protrusions arranged in a non-compressed state. Further, grease is stored in a part or all of the concavities formed by the main protrusions and the sub-protrusions.

Abstract: A steering apparatus includes a steering shaft; a steered shaft; a ball screw mechanism; and a motor. A plurality of rolling elements includes large-diameter rolling elements and small-diameter rolling elements. A prescribed diameter difference is set such that when a magnitude of power transmitted between a first screw groove and a second screw groove is a prescribed value or less, only the large-diameter rolling elements transmit the power between the first screw groove and the second screw groove, and when the magnitude of the power transmitted between the first screw groove and the second screw groove exceeds the prescribed value, both the large-diameter rolling elements and the small-diameter rolling elements transmit the power.

Abstract: This torque limiter is configured from a ring body and a spring-form part provided in the ring body. The ring body comprises a band-form metal plate and is bent approximately into a C-shape along the circumferential direction of a motor shaft and a lock holder. The spring-form part is formed so as to be capable of radial elastic deformation. The spring-form part is configured from main protrusions arranged in a compressed state between the motor shaft and the lock holder, and from sub-protrusions arranged in a non-compressed state. Further, grease is stored in a part or all of the concavities formed by the main protrusions and the sub-protrusions.

Abstract: This torque limiter is configured from a ring body and a spring-form part provided in the ring body. The ring body comprises a band-form metal plate and is bent approximately into a C-shape along the circumferential direction of a motor shaft and a lock holder. The spring-form part is formed so as to be capable of radial elastic deformation. The spring-form part is configured from main protrusions arranged in a compressed state between the motor shaft and the lock holder, and from sub-protrusions arranged in a non-compressed state. Further, grease is stored in a part or all of the concavities formed by the main protrusions and the sub-protrusions.

Abstract: This torque limiter is configured from a ring body and a spring-form part provided in the ring body. The ring body comprises a band-form metal plate and is bent approximately into a C-shape along the circumferential direction of a motor shaft and a lock holder. The spring-form part is formed so as to be capable of radial elastic deformation. The spring-form part is configured from main protrusions arranged in a compressed state between the motor shaft and the lock holder, and from sub-protrusions arranged in a non-compressed state. Further, grease is stored in a part or all of the concavities formed by the main protrusions and the sub-protrusions.

Abstract: A variable transmission ratio apparatus for effectively preventing ratcheting between a flexible spline and a circular spline caused by a steering operation performing in a locked state. A variable transmission ratio apparatus includes a strain wave gear mechanism for adding rotation resulting from motor drive to rotation from an input shaft resulting from a steering operation and transmitting the added rotation to an output shaft, a housing accommodating the strain wave gear mechanism and the motor and fixed to a non-rotating portion, and a lock device for locking the housing and a motor shaft in a manner prohibiting relative rotation therebetween. Among the circular splines forming the strain wave gear mechanism, the number of teeth of the circular spline connected to the output shaft is greater than the number of teeth of the circular spline connected to the input shaft.

Abstract: A variable transmission ratio apparatus for effectively preventing ratcheting between a flexible spline and a circular spline caused by a steering operation performing in a locked state. A variable transmission ratio apparatus includes a strain wave gear mechanism for adding rotation resulting from motor drive to rotation from an input shaft resulting from a steering operation and transmitting the added rotation to an output shaft, a housing accommodating the strain wave gear mechanism and the motor and fixed to a non-rotating portion, and a lock device for locking the housing and a motor shaft in a manner prohibiting relative rotation therebetween. Among the circular splines forming the strain wave gear mechanism, the number of teeth of the circular spline connected to the output shaft is greater than the number of teeth of the circular spline connected to the input shaft.

Abstract: In a control unit for an electrical-motor-driven power steering apparatus, there are provided an assist current command value calculated based upon a steering torque of a steering wheel, an assist current control value calculated based upon a motor current value of a motor and the assist current command value. A motor outputs an assist force based upon the assist current control value. Further, the control unit provides an estimation means for estimating a road surface &mgr; based upon at least one of the motor current value and the steering torque. To the control unit, there are further inputted a vehicle speed obtained based upon rotation of a wheel, and a steering angle obtained based upon rotation of the steering wheel. Therefore, the estimation means estimates the road surface &mgr; by comparing with a previously memorized standard value corresponding to the vehicle speed and the steering angle.

Abstract: In a control unit for an electrical-motor-driven power steering apparatus, there are provided an assist current command value calculated based upon a steering torque of a steering wheel, an assist current control value calculated based upon a motor current value of a motor and the assist current command value. A motor outputs an assist force based upon the assist current control value. Further, the control unit provides an estimation means for estimating a road surface &mgr; based upon at least one of the motor current value and the steering torque. To the control unit, there are further inputted a vehicle speed obtained based upon rotation of a wheel, and a steering angle obtained based upon rotation of the steering wheel. Therefore, the estimation means estimates the road surface &mgr; by comparing with a previously memorized standard value corresponding to the vehicle speed and the steering angle.